Magento writes system.log with log disabled

Question

I disabled logging from the System > Advanced > Developer screen (I've checked that is disabled for all the websites/stores/storeviews) but Magento continues to write errors inside "/var/log/system.log" like:

[...] ERR (3): Warning: simplexml_load_string(): [...] in /lib/Varien/Simplexml/Config.php on line 383

Are there errors that ignore the admin backend setting?

Answer 1

I have found that there was an extension with invalid xml data in one of its files, specifically a tag starting with a number.

<123abc></123abc>

Answer 2

In app/Mage.php method log():

    if (!self::$_isDeveloperMode && !$logActive && !$forceLog) {
        return;
    }

A log will be written if the system is in developer mode, or the log is active, or the $forceLog parameter is true.

Since you say logging is disabled, and since the error handler does not force logging (as defined in app/code/core/Mage/Core/functions.php::mageCoreErrorHandler()), your store most likely has developer mode enabled. Check your .htaccess and index.php files for anything that might be triggering that.

Answer 3

I guess there is an Mage::log() call with param $forceLog = true:

    public static function log($message, $level = null, $file = '', $forceLog = false)